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A method has been developed which allows a reduction in magnetic noise of induction machines by injecting current harmonics. Its achievement needs an accurate knowledge of the flux density harmonics in the airgap of the machines. First, the principle of the magnetic noise generation is reviewed. A fictitious slot model allows one to determine the airgap permeance expression and, multiplying this last one by the expression of the magnetomotive force distribution, to define the flux density harmonics. The stator harmonics are described. They induce electromotive forces and currents into the rotor conductors which generate rotor flux density harmonics. The knowledge of those quantities allows to calculate the Maxwell forces which can generate magnetic noise. A method of noise reduction is then explained. Its principle is to inject a small controlled current harmonic into the stator windings in order to create a supplementary force wave which opposes those contributing to noise. A small supplementary current allows a reduction of magnetic noise in a big machine. The method limits, precisions, calculations, control principles and injection ways, are described in order to know if the noise of a motor can be reduced and how to do it. Experimentations illustrate those descriptions.

This paper presents a comparative study for two frequency control strategy applied to a self excited induction generator equipping a wind turbine in remote site. This study was conducted through the analysis of the frequency in the steady state and transient case using a developed induction generator numerical model. The simulation results obtained by numerical model are validated using an experimental test bench. For frequency control a fuzzy logic controller is presented in the paper and validated using Matlab-Simulink environment. The simulation results obtained by fuzzy controller are compared with those provided by a specific law obtained from analytical study of induction generator.

The aim of this paper is to contribute to the electrical machine diagnosis running as adjustable speed drive. The analyzed signal is the leakage flux flowing around the machine, which is considered to be an image of the airgap flux density. An analytical expression of the airgap flux density is presented and gives sensitive spectral lines to a stator winding short-circuit fault in an induction machine. The study is done on a frequency range up to few kilohertz, around the slotting spectral lines. The originality of this paper is that the study is focused on machines fed by the mean of a converter. The theory is verified by experimental tests and the results show what precautions are necessary to take in order to obtain spectra which can be used for diagnosis.

The aim of this paper is to present the advantage of stator fault detection using an external leakage flux sensor in working induction machine. In this paper, it is proved that a simple external leakage flux sensor is more efficient than a stator current sensor to detect intern-turn short circuit in three-phase induction machines. The new result is that, even in presence of power supply harmonics, it is possible to detect easily the stator winding faults in the low frequency range of the leakage flux spectrum with low frequency resolution.

The aim of this paper is to show quantitatively how external radial magnetic field spectral lines vary when a short-circuit fault appears on induction machine stator winding. The sensitivity of the spectral lines to the fault is estimated by changing the ratio of the shorted turn current comparatively to the supply current. For a given position of the used sensor, the sensitivity of particular spectral lines is also analysed depending on the location of the fault in the stator winding

The effects of the battery current created by a charger operating in power factor correction (PFC) mode is investigated. In this case, the charging current contains a sinusoidal perturbation. This could deteriorate the performance of the charge compared to the classic charging technique, which uses a constant current. A dynamical model of the battery is proposed which facilitates an explaination of the contribution of the sinusoidal perturbation on the performances of a lead-acid battery. This theoretical facilitates the supposition that the DC component of the charging current is at the origin of the charge. This assumption is validated by the experimental results which show that the sinusoidal perturbation has no effect on the electrical performance of a lead-acid battery.

This paper presents several methods which allow characterisation of the order, the rank and the magnitude of three-phase harmonic systems generated by PWM inverter switching. In a second part, the authors describe an active magnetic noise reduction which controls the harmonic currents due to the switching in order to generate forces. These last are controlled to act in opposition with the forces due to the slots.